Displacement detection sensor using magnetostriction

Abstract

A displacement detection sensor includes a wire having one end portion and a second end portion, extending along a direction such that the second end portion is connected to a fixed position; a magnet generating a magnetic field therefrom, movable along the wire such that the wire is always being placed in the magnetic field and producing a twist in the wire when a current is supplied to the wire after a displacement of the magnet from its original to rest positions; a receiving device for receiving an elastic wave traveling directly to one end portion of the wire which is caused by the twist in the wire, the receiving device having a current induced thereat; an analyzing device for calculating the displacement on the basis of a time point at which the current is applied to the wire, and another time point at which the current is induced at the receiving device; and a tension device positioned at one end side of the wire for giving tension to the wire.

What is claimed is: 
     
       1. A displacement sensor comprising: a wire having one end portion and a second end portion, extending along a direction such that the second end portion is connected to a fixed position, the wire being composed of magnetostrictive material;   a magnet generating a magnetic field therefrom, movable along the wire such that the wire is always being placed in the magnetic field and producing a twist in the wire when a current is supplied to the wire after a displacement of the magnet from its original to rest positions;   receiving means for receiving an elastic wave traveling directly to one end portion of the wire which is caused by the twist in the wire, wherein the receiving means has a current induced thereat;   analyzing means for calculating the displacement on the basis of a time point at which the current is applied to the wire, and another time point at which the current is induced at the receiving means; and   a tension means positioned at one end side of the wire for giving tension to the wire, and for damping the elastic wave transmitted through the wire, wherein the tension means has a plate fixed on the wire and an elastic member compressed between the plate and one end of the receiving means,   wherein the elastic member is in taper-to-taper elastic engagement with one end portion of the receiving means.   
     
     
       2. A displacement detection sensor comprising: a wire having one end portion and a second end portion, extending along a direction such that the second end portion is connected to a fixed position, the wire being composed of magnetostrictive material;   a magnet generating a magnetic field therefrom, movable along the wire such that the wire is always being placed in the magnetic field and producing a twist in the wire when a current is supplied to the wire after a displacement of the magnet from its original to rest positions;   receiving means for receiving an elastic wave traveling directly to one end portion of the wire which is caused by the twist in the wire, wherein the receiving means has a current induced thereat;   analyzing means for calculating the displacement on the basis of a time point at which the current is applied to the wire, and another time point at which the current is induced at the receiving means; and   a tension means positioned at one end side of the wire for giving tension to the wire, and for damping the elastic wave transmitted through the wire, the tension means having a plate fixed on the wire and an elastic member compressed between the plate and one end of the receiving means.   
     
     
       3. A displacement detection sensor as set forth in claim 1, wherein the analyzing means includes a microprocessor and calculates the displacement in plural times at very short intervals.